Electron tube electrode



Aug. 18, 1959 I w. K. BATZLE ELECTRON TUBE ELECTRODE Filed March 22, 1956 Maj COMPREJS/d/V sxozv INVENTOR. WILLIFIM Bn-rzuz BY MW i 44 COMP/P58 NE Y Unit Sta es Patent r ELECTRON TUBE ELECTRODE William K. Batzle, Bloomfield, N.J., assignor to Radio Corporation of America, a corporation of Delaware Application March 22, 1956, Serial No. 573,187

7 Claims. (Cl. 313-331) The present invention is concerned with a sheet metal electron tube electrode of the 'type having a tab for connection to a lead-in wire and, while not limited thereto, is herein described with respect to a tubular cathode sleeve for an indirectly heated cathode having an integral tab.

Elongated electrodes, such as sleeve type cathodes having a curved transverse extent and an integral, longitudinally extending tab, are known. In such electrodes the tab usually follows the curvature of the electrode body. In welding a lead-in wire to the tab of such an electrode, it is usually desirable to bend the tab in a direction away from the axis of the electrode. However, this bending has not been satisfactory, since it often results in a breaking off of the tab at the site of the bend. For example, when the electrode is a tubular, indirectly heated cathode, and the tab extends longitudinally from the cathode sleeve, the tab must be bent laterally away from the axis of the sleeve before a lead-in wire is fixed to the tab in order to avoid contact between the lead-in wire and a cathode heater which is positioned within the interior of the sleeve. When the tabis made integral with the sleeve, the tab usually has the same curvature as the sleeve thus, when the tab is bent away from the axis of the sleeve, the tabis bent in a direction wherein the cross-sectional curvature of the tab causes a rupture or break therein.

One object of the invention is to provide an improved electrode having an elongated body with a curved transverse extent and having an integral, longitudinally extending tab which is adapted to be bent in a direction away from the body without rupturing or breaking off.

Another object of the invention is to provide an improved cathode sleeve having an improved integral tab.

' The foregoing and related objects are accomplished in a novel electrode according to the invention. The novel electrode comprises an elongated sheet metal body having a curved transverse extent and a tab extending from one end of said body in axially parallel relation thereto and having a transverse extent curved in a direction different from that of the body. The tab can be bent in the different direction without breaking off since the tab would then be bent in the same direction as that of its curvature.

The invention is described in greater detail in the connection with the accompanying single sheet of drawing wherein:

Fig. 1 shows an electron tube partly broken away and containing an improved cathode sleeve constructed in accordance with the principle of the invention;

Fig. 2 is a perspective view, on an enlarged scale, of an end portion of the cathode sleeve of the tube shown in Fig. l;

Fig. 3 is a sectional view of the cathode sleeve taken along line 3-3 of Fig. 2; and

Fig. 4 is a perspective view of a length of ribbon-like sheet metal having a transverse curve and bent in a direction to avoid breakage thereof; and

Fig. 5 is a perspective view of another length of ribbonlike sheet metal having a, transverse curve as in Fig. 4,

to e

but bent in a different direction from in Fig. 4.

Referring now in greater detail to the drawing, there is shown in Fig. 1 an electron tube 10 having an envelope 12, a base 14 having electrode access terminals or prongs 16, and an electrode assembly 17. The electrode assembly 17- includes an anode 18, a grid 20, and a cathode 22. The cathode 22 includes a heater 23, and a cathode sleeve 32 having an integral tab 24 connected to a lead-in wire 26 which is, in turn, connected to one of the prongs 16. The electrodes 18, 20, and 22 are maintained in the desired position relative to each other by a pair of insulating spacer plates 28 and 30.

The cathode 22 includes a cathode sleeve in the form of a cylindrically tubular body 32 having the integral tab 24. The tab 24, before it is mounted within the tube 10, extends longitudinally from the cathode sleeve 32. This position of longitudinal extension is illustrated in Fig. 2 by dashed lines 24a. Since the cathode sleeve 32 has a tubular form, it has an inwardly facing concave transverse extent. The tab 24, however, is provided with a reverse curvature, that is, a curvature opposite to that of the body of the sleeve 32 from which the tab extends. Consequently, the tab 24 has an outwardly facing concave curvature. This reverse curvature extends for a short distance A along the body of the sleeve 32 so that the tab is provided with the same direction of the bend shown curvature as that of the adjacent portion 33 (Figs. 2: and 3) of the sleeve 32. The tab 24, consequently, may

bent in the direction of its concavity withoutrupturing' or breaking off, and Fig. 5 is similarly marked in explanation of the reason why the aforementioned tabmay rupture or break off if bent in a direction opposite its concavity. As is known, if a piece of sheet metal adjacentto an edge is subjected to tensile stress, the strained portion will tend to tear in a direction inwardly from that edge. Referring to Fig. 4, if a piece of sheet metal ribbon 50 having a curved transverse extent is bent in the direction of its curvature (the bend at letter C) the' central portion 52 of the ribbon 50 will be subjected to tensile stress while the edge portions 54 and 56 will be subjected to compressive stress.

52 under tensile strain is bounded on both sides by portions 54 and 56 under compressive strain the centralportion 52 does not have a weak spot (e.g. an edge) from which a tear may develop. Consequently, the bend is free from tearing. On the other hand and as shown in Fig. 5, if the ribbon is bent in a direction opposite to its direction of curvature (the bend at letter D) the edge portions 60 and 62 of the ribbon 50 will be subjected to tensile stress while the central portion 64 will be subjected to compressive stress. Since the portions 60 and 62 under the tensile strain are each bounded on one side by an edge of the ribbon 50, these portions will tend to tear at the edges as illustrated in the drawing. Therefore, to avoid a rupturing or breaking of a sheet metal body having a curved transverse extent, the body should be bent in the same direction as that of the curvature of the body.

in order that the heater may be inserted into the sleeve. However, it is desirable that the clearance or spacing be-c Patented Aug. 18, 1959 Since the portion tween the heater 23 and the sleeve 32 be as small as possible in order that the sleeve be in good thermally conductive relation with the heater. Consequently, the

reverse tab curvature aforementioned cannot beprovided b'y'dep'ressing inwardly the tab and the portion of the,

sleeve adjacent thereto. The reason for this is that the depressing would reduce the diameter of the sleeve at the portion thereof adjacent to the tab and would consequently hinder, if not prevent, the subsequent insertion of the heater into the sleeve.

1 Therefore, according to another feature of the invention, the tab 24 is provided with the required reverse curvature without reducing the inside diameter of the cathode sleeve. In order to maintain the minimum in side transverse extent of the sleeve 32 in the region of the tab the same as that in the rest of the sleeve, the sleeve is provided with a pair of outwardly extending embossments 34 and 36 adjacent to each long edge 38 and 40 of the tab 24 at the place where the edges meet the sleeve 32. These embossments 38 and 40 provide the sleeve 32, at the portion thereof adjacent to the tab 24, with a larger transverse dimension or extent than the rest of the sleeve. Consequently, the tab and the portion of the sleeve between the embossments can be depressed so as to provide the tab with the aforementioned reverse curvature. Thus, the tab may be provided with a curvature opposite that of the sleeve without reducing the diameter of the sleeve.

It will be apparent from the foregoing description of the invention that an improved electrode structure is provided with is better adapted to have a. portion thereof bent for connection to'a lead-in wire without a rupturing or a breaking of the electrode portion.

What is claimed is:

1. An electrode comprising an elongated tubular sheet metal body having a portion of major transverse extent concave in one direction and a longitudinally extending bendable tab having a transverse extent concave in a direction other than said one direction, the portion of said body coextensively adjacent to said tab having a minor transverse extent and a curvature in the same direction as that of said tab, whereby said tab is adapted to be bent in said other direction while being preserved from rupture, said portion of said body being at least as remote from the axis of said body as said portion of major transverse extent, whereby the space within said tubular body is preserved from encroachment.

2. A hollow cathode sleeve for an indirectly heated cathode having a heater, comprising a tubular body having a curved transverse extent and a longitudinally extending bendable tab having a concave curvature in a direction opposite that of said body, said body having a pair of longitudinally extending embossments adjacent to each long edge of said tab at the place where said edges meet said body, said embossments extending outwardly from a side of said body a distance to dispose the portion of said body between said embossments and coextensive with said tab at least as remote from the longitudinal axis of said body as said curved transverse extent, whereby said sleeve is adapted to receive said heater along substantially the entire longitudinal extent of the hollow of said sleeve.

3. A hollow sleeve for an indirectly heated cathode having a heater, comprising a tubular body having a curved transverse extent and a longitudinally extending bendable tab having a concave curvature in a direction opposite that of said body, said body having a pair of longitudinally extending embossments adjacent to each long edge of said tab at the place where: said edges meet said body, said embossments extending outwardly from aside of said body, said tab extending inwardly for a less transverse extent than the outward extent of said embossments, whereby said sleeve is adapted to receive said heater along substantially the entire longitudinal extentof the hollow of said sleeve.

4. The sleeve described in claim 3 and wherein the portion of said body adjacent to said tab has a curvature" in the same direction as that of said tab, whereby said tab is adapted to be bent in said opposite direction while being preserved from rupture.

5. The sleeve described in claim 3 and wherein said tubular body comprises a hollow cylinder.

6. An electron tube comprising a pair of spacer plates, a plurality of electrodes secured between said plates, one of said electrodes including a hollow cathode sleeve of the type adapted to receive a heater and extending through said plates and comprising a tubular body having a curved transverse extent and a longitudinally extending tab having a concave curvature in a direction opposite that of the tubular body, said body having a pair of longitudinally extending embossments one adjacent to each long edge of said tab at the place where said long edges meet said body, said embossments extending outwardly from a side of said body and engaging one of said plates for locking said one of said electrodes thereto, said tab having a portion thereof adjacent to said body extending inwardly for a less transverse extent than the outward extent of said embossments, and the free end of said tab being bent in a direction radially away from said body, whereby said one of said electrodes is adapted to have one transverse extent for insertion through said plates and to have said tab bent into a larger transverse extent for facilitating the establishment of an electrical connection thereto, while preserving said sleeve from an indirectly heated cathode and extending through saidplatesand comprising a tubular body having a curved transverse extent and a longitudinally extending tab having a concave curvature in a direction opposite that of the tubular body, said body having a pair of longitudinally extending embossments one adjacent to each long edge of said tab at the place where said long edges meet said body, said embossments extending outwardly from a side of said body and engaging one of said plates for locking said one of said electrodes thereto, said tab having a portion thereof adjacent to said body extending inwardly for a less transverse extent than the outward extent of said embossments, and the free end of said tab being bent in a direction radially away from said body, the portion of said body adjacent to said tab and between said embossments having a curvature in the same direction as that of said tab and having the same magnitude of inward extension as that of said tab portion, whereby said one of said electrodes is adapted to have one transverse extent for insertion through said plates and to have said tab bent into a larger transverse extent for facilitating-the establishment of an electrical connection thereto, 1

while preserving said sleeve from deformation for receipt of a heater therefor along substantially the entire longitudinal extent of the hollow of said sleeve.

References Cited in the file of this patent UNITED STATES PATENTS 

